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Oxygen abundance in coronal streamers during solar minimum
Giordano, S.; Antonucci, E.; Marocchi, D.
We present a study of the oxygen abundance relative to hydrogen in the equatorial streamer belt of the solar corona during the recent period of activity minimum. The oxygen abundance is derived from the spectroscopic observations of the outer corona performed during 1996 with the Ultraviolet Coronagraph Spectrometer (SOHO) in the ultra-violet regi…
An ICME observed by Voyager 2 at 58 AU and by Ulysses at 5 AU
Wang, C.; Heber, B.; von Steiger, R. +1 more
Between days 175 and 180 (June 24 through 29) of 1999, the PLS instrument on Voyager 2 observed alpha particle enhancements with fractional percentages of alpha to proton number densities exceeding 10%. Ulysses (located at 5.3 AU) observed at least two candidate source features for these enhancements. To identify the correct source structure, a 1D…
UV observations of the galaxy cluster Abell 1795 with the optical monitor on XMM-Newton
Kaastra, J. S.; Fabian, A. C.; Mushotzky, R. F. +8 more
We present the results of an analysis of broad band UV observations of the central regions of Abell 1795 observed with the optical monitor on XMM-Newton. As have been found with other UV observations of the central regions of clusters of galaxies, we find evidence for star formation. However, we also find evidence for absorption in the cD galaxy o…
The LMC eclipsing binary HV 2274 revisited
Salaris, M.; Groenewegen, M. A. T.
We reanalyse the UV/optical spectrum and optical broad-band data of the eclipsing binary HV 2274 in the LMC, and derive its distance following the method given by Guinan et al. (\cite{Guinan98a},\cite{Guinan98b}) of fitting theoretical spectra to the stars' UV/optical spectrum plus optical photometry. We describe the method in detail, pointing out…
Constraints on thick disc and halo parameters from HST photometry of field stars in the Galaxy
Santiago, B. X.; Kerber, L. O.; Javiel, S. C.
We analyse a sample of over 1000 stars from 32 fields imaged in the V and I bands with the Wide Field and Planetary Camera, on board of the Hubble Space Telescope. The fields are located at Galactic latitudes | b | >= 15deg and in various directions on the sky. We consider models for the structure of the Galaxy with different choices…
RX J0848+4456: Disentangling a Moderate Redshift Cluster
Papovich, C.; Tozzi, P.; Rosati, P. +7 more
We present a multiwavelength study of RX J0848+4456, a cluster of galaxies discovered through X-ray emission in the ROSAT Deep Cluster Survey. Our observations consist of WFPC2 imaging, optical spectra, and X-ray data collected with the Chandra X-Ray Observatory. We find that RX J0848+4456 consists of an X-ray-emitting cluster of galaxies at a red…
Observations of the Interstellar Medium in the Magellanic Bridge
Sembach, K. R.; Dufton, P. L.; Keenan, F. P. +2 more
We present ultraviolet and optical spectra of DI 1388, a young star in the Magellanic Bridge, a region of gas between the Small and Large Magellanic Clouds. The data have signal-to-noise ratios of 20-45 and a spectral resolution of 6.5 km s-1. Interstellar absorption by the Magellanic Bridge at vLSR~200 km s-1 is v…
Deep Near-Infrared Luminosity Function of a Cluster of Galaxies at Z=0.3
Andreon, S.
The deep near-infrared luminosity function of AC 118, a cluster of galaxies at z=0.3, is presented. AC 118 is a bimodal cluster, as evidenced both by our near-infrared images of lensed galaxies, by public X-ray ROSAT images, and by the spatial distribution of bright galaxies. Taking advantage of the extension and depth of our data, which sample an…
Physical parameters of sdB stars from spectral energy distributions
Jeffery, C. S.; Aznar Cuadrado, R.
The atmospheric parameters of 34 hot subdwarf B stars have been obtained using a combination of 61 short and long-wave IUE spectra, together with new and existing optical and infrared photometric data. Using a grid of high-gravity helium-deficient model atmospheres and a chi 2-minimization procedure, 15 single sdB stars and 19 composite…
Photoelectric effect on dust grains across the L1721 cloud in the rho Ophiuchi molecular complex
Boulanger, F.; Habart, E.; Pineau des Forêts, G. +3 more
We present ISO-LWS measurements of the main gas cooling lines, [C+] 158 mu m and [O0] 63 mu m towards a moderate opacity molecular cloud (Av ~ 3), L1721, illuminated by the B2 star nu Sco (chi = 5-10). These data are combined with an extinction map and IRAS dust emission images to test our understanding of gas heat…